Quickly

NEW YORK — The new Louis Armstrong Stadium wasn't yet two hours old when it hosted its first historic upset: Simona Halep became the first top-seeded woman in the Open Era to lose in the first round of the U.S. Open. That ended up being the biggest storyline on a day that saw former Grand Slam champions move on as well as two young players score much-needed victories.

Here are five thoughts from Day 1 at Flushing Meadows.

• As omens go, you could do better. The new, roofed Louis Armstrong was christened by Simona Halep, the top seed whom—we were led to believe—had committed personal democide when she won the French Open in June. Not so fast. Halep’s gremlins were in full force on Monday. She sprayed balls, cracked her racket and looked like something decidedly other than a champion, falling 6-2, 6-4 to Kaia Kanepi, a 33-year-old Estonian ranked 44th in the world. If there’s good news, Halep will likely keep her top spot, given that she lost in the first round here as well in 2017 (as the No. 2 seed) and thus won’t drop ranking points. But this is a dismal, dismal loss that reverses a fair bit of Halep’s 2018 progress and puts a stain on an otherwise great year. Her loss also opens the draw for those in her neighborhood of the draw, not least…

• It was 21 years ago that Venus Williams made her first U.S. Open final. It was 19 years ago that Serena Williams not only reached the final, but won the title, the first of her 23 (and counting) Slams. Here they are, ages 38 and almost 37 still contending. In a spellbinding (if unnecessarily difficult) afternoon match, No. 16 seed Venus got past another former champion, Svetlana Kuznetsova, in three sets. After a musical interlude from Kelly Clarkson, 17th-seeded Serena—still the WTA’s headliner, rankings be damned—opens the session tonight. We could well see an All-Williams Bowl in the third round, less a match than an opportunity to celebrate these dual forces, their contributions and their longevity.

• You imagine a casual tennis fan in Arthur Ashe Stadium, watching the first match of the day and thinking a titanic upset had just occurred. After all, world No. 101 Stan Wawrinka took out top-10 stalwart Grigor Dimitrov, seeded 8th here, in straight sets. This, of course, was an upset on paper and pixels only. For the second-straight major, Wawrinka bullied Dimitrov in a first-round matchup, won the battle of one-handed backhands and prevailed fairly handily. After missing last year’s tournament with a knee injury, Wawrinka, the 2016 U.S. Open champ, has now won eight straight matches at Flushing Meadows. And as his draws opens, he emerges as a real threat. This summer on hard courts, Wawrinka lost a tight match to Nadal (the eventual winner) in Toronto and a three-setter to Djokovic (the eventual winner) in Cincy. Want an unsung player to follow at this event? Look no further than Stan.

• Speaking of three-time Slam winners on the mend...Andy Murray still doesn’t look 100% after hip surgery. But he’s still competing and still bringing his mix of cerebral and physical tennis to bear. In his first major appearance in 14 months, Murray overcame a shaky first set and beat Australian James Duckworth in 6-7, 6-3, 7-5, 6-3. In other years, this result would represent a ho-hum early win for a player expected to advance deep into the tournament. This year, it carries far more significance. (As Murray was winning, his countryman, No. 16 seed Kyle Edmund, was losing disappointingly, in four sets to Paolo Lorenzi.)

• Two players in need of wins found them. Jack Sock started the year in the top 10. But coming into this event, he’d won five matches the entire year and none since the spring. Late August is certainly late to start a season, but better late than never. Sock was terrific today, beating Guido Andreozzi, of Argentina, handily. If he wins his next match against Nikoloz Basilashvili, it would be his first back-to-back wins of 2018.

A year ago Garbine Muguruza was a Wimbledon champ who looked like the strongest candidate to fill the vacuum created by Serena Williams’ absence. This year, she has been dismal and disappointing, losing early and often and looking detached in the process. After losing her lone match post-Wimbledon, she entered this event ranked No. 12. Today, though, she looked like a contender, with a tidy 6-3, 6-0 win over Zhang Shaui. It would be completely in keeping with Muguruza’s rhythms if she made a deep run with little warning signs.